Acoustic tile



A. B. HU RLEY Nov. 5, 1946.

ACOUSTIC TILE Filed Feb. 10, 1 945 2 She ets-Sheet 1 I INVENTOR vlbert'B. Hurley r ATTORNEYS Patented Nov. 5, 1946 UNITED STATES PATENTOFFICE ACOUSTIC TILE 7 Albert B. Hurley, Huntington, N. Y. ApplicationFebruary 10, 1943, Serial No. 475,349 (01. 154-44) Claims.

This invention relates to an improved acoustic tile for wall structuressuch as ceilings and side walls for purposes of sound control.

The prime desideratum of my present invention centers about theprovision of an improved acoustic tile designed for high efllciencyabsorption of sound over a wide range or over the spectrum of audiblesound frequencies.

Acoustic wall structures have been made in various forms, and commonlyas pads, slabs and blocks of a porous material such as felt, mineralwool, wood fibre, porous gypsum or other vegetable or mineral fibres.Some of these products rely solely on the porosity of the material,while others additionally provide holes in the material in an effort toimprove the sound absorption. The sound absorption is due to the porousnature of the material and to the heat consumed by friction generated inthe interior by sound waves traversing the fibrous mass.

In such acoustic wall structures it is found that the sound absorptionefficiency is substantially greater for higher audible frequencies thanfor the low frequencies. In my copencling application, Serial No.402,793, filed July 17, 1941, for a Vibratable board for acoustictreatment, I disclose an acoustic tile or board designed for absorbingsound frequencies both over the higher and lower ranges, the board ortile, constructed for the usual absorption of high frequencies, beingdesigned so as to provide a vibratable center or diaphragm portion whichacts to enhance the, dampening or absorption efficiency of the board ortile for low frequency sound.

The prime object of my present invention pertains to the provision of anacoustic tile made of a sound absorbing, material embodying a structurewhich provides an increased area and a broken exposed surface forimproved high frequency sound absorption and a vibratable body portionfor improved low frequency sound absorption. The structure is,therefore, designed for high efficiency sound absorption over thespectrum of audible sound frequencies.

A further object of the invention relates to the provision of anacoustic tile in which the mecham'cal design pennits of predetermlningor controlling the range of absorbable sound frequencies, to meetdifferent acoustic problems'that. present themselves in service. Thetiles of the invention may be made with one or more predeterminednatural vibration frequencies, and the same or different frequency tilesmay be applied to a wall or ceiling, uniformly or in appropriatelystaggered arrangement, to meet or solve "1e 2 acoustic problem raised inany particular installation.

A still further object of the invention relates to the provision of anacoustic tile of the nature referred .to, the structure of which isattractive and in fact highly ornamental in appearance.

To the accomplishment of the foregoing and such other objects as willhereinafter appear, my invention consists in the acoustic tile featuresand their relation one to the other as hereinafter are more particularlydescribed in the specification' and sought to be defined in the claimsThe specification is accompanied by drawings, in which:

Fig. l is a plan view of the improved acoustic tile of my presentinvention;

Fig. 2 is a view thereof taken in cross-section in the plane of the line2---2 of Fig. l;

Fig. 3 is a view showing a number of sue acoustic tiles applied to awall structure;

Fig. 4 is a view of the latter taken in crosssection in the plane of theline 4--4 of Fig. 3;

Fig. 5 is a plan view of a slab or board showing one manner in which thesections of an acoustic tile of th present invention may be cut out orexcised from a slab or board;

Fig. 6 is a view of Fig. 5 taken in cross-section in the plane of theline 6-5 of Fig. 5;

Fig. 7 is an exploded view taken in cross-section and showing the mannerof rearranging the cutout parts of Figs. 5 or 6 in the step of assemblinthe same to form an acoustic tile of the present invention; 1

Fig. 8 is another plan view of the assembled acoustic tile, showing,however, a modification thereof;

Fig. 9 is a view of Fig. 8 taken in cross-section in the plane of theline 9--9 of Fig. 8;

Fig. 10 is a. cross-sectional view corresponding to the view shown inFig. 6 but showing a modification thereof;

i 11 is an assembled view of an acoustic tile made from the partsorsections of the tile slab or board shown in Fig. 10;

Fig. 12 is a perspective fragmentary view of a part of the base piece orsection of the tile showing certain features of construction;

Fig. 13-is a cross-sectional view of another modification showing adifferent method of as sembling the sections of the tile; and

Fig 14 is a cross-sectional view of a still further modification.

Referring now morein' detail to the drawings and having reference firstto Figs. 1 and 2therethe aqq lfitiu tile of the present inventioncomprises a tile unit generally designated as T made of a suitable soundabsorbing material and consisting of a plurality of tile sections suchas the sections or pieces a, b, c, d and e of progressively decreasingsize, arranged in stepped relation as clearly depicted in these figures.The tile sections or pieces may be formed in any desired way and made ofa porous material such as felt, mineral wool, wood fibre, porous gypsumor other vegetable or mineral fibres suitably processed and compacted toproduce a light-weight porous sound deadening or absorbing product. Thetile unit 'I' may be molded in one piece if desired, to produce theconfiguration such as shown, for example, in Figs. 1 and 2 of thedrawings, and in the preferred construction as will appear here--inafter, the tile sections or pieces are cut oriabri cated from slabs orboards of the porous material and thereafter assembled to produce theunit as typically shown in Figs. 1 and 2 of the drawings.

One of the objects of the present invention per tains to the provisionof an acoustic tile made of a sound absorbing material and embodying astructure which provides an increased area and a broken exposed surfacefor improved sound absorption and particularly for improved soundabsorption of the higher sound frequencies. This is accomplished byhaving the tile sections of the tile unit, whether made integrally or inassembled separate pieces, built up with the sections of progressivelydecreasing size arranged in stepped relation, as shown, for example, inl and 2 of the drawings, to form a generally pyramidal type unit.

The other main object of the present invention pertains to the provisionof an acoustic tile in which there is provided a vibratable body portionfor improved low frequencies sound absorp-- tion, the vibratable bodyportion acting in enhance the dampening or absorption efilciency of thetile for low frequency sound. This is accomplished by so designing thesections or pieces a to e of the tile unit as to provide a central. bodyportion which is vibratable as desired. Generlcally this tile unitconsists of the base section or piece a formed as an annulus, the top orapex piece e formed as a plaque, and one or more intermediate pieces b,c and d, each also formed as an annular member, interconnecting instepped relation the apex piece 6 and the base piece a. The annularpieces a to d and the plaque piece 2 may be made in any suitable contoursuch as round, triangular, square or other shape, the square shape beingillustrated in the drawings. When made of separate pieces assembled toform the pyramidal unit, the contiguous contactin faces such as 10, H,I! and H (see Fig. 2) of the pieces are joined together as by means of asuitable adhesive.

By means of this construction, the following results are achieved:

(a) The surface of the acoustic tile exposed to the sound waves isconsiderably increased. For each the section or piece such surface nowcomprises a front exposed face or wall and side faces or walls. Thus,for the plaque piece c the exposed surface consists of the front surfaces and the side wall surface-s s, s. The same is true for each of theother pieces or sections of the tile and such parts are designated bysimilar reference characters. When the tile is made by cutting out thesections thereof from slabs or boards of a sound absorbing material, themore porous body oithe tile material becomes exposed. 1. 11

, is indicated in Fig. 1 of the drawings wherein it is shown that thecut or excised surfaces 5' are more porous than the finished surface sof the tile board. When so made, not only is there an increaseinthe'total area of absorbing material, but a great portion of the thusexposed area being more porous is more highly absorbent of the sound.

(b) The angularly broken surfaces s, s, s, etc., presented by thestepped tile pieces also acoustically cause the breaking up anddispersion of the sound waves incident upon the tile.

(0) The base supported pieces or sections b, c, it and e (or a part ofthese if a less number of these pieces is used) present vibratablediaphragm for the sound absorption of the lower frequencies. A veryimportant feature of this part of the construction is the air spacegenerally designated as i i (Fig. 2) clcsignodly formed in the regionbetween. the tile sections and the supporting wall or ceiling therefor,which air space allows each tilc to act more cihciently as a diaphragmwith consequent dampening of any sound waves striking the same.

A number of tile units of the type shown in Figs. 1 and 2 may beassembled. to i'orrn a ceiling or side wall structure after the mannershown in Figs. 3 and 4 of the drawings. The base section a oi" each ofthese tile units T may be suitably chamlered on two sides as at l5 andgrooved at its other two sides as at 18, as best shown in Figs, 2 and 12of the drawings, so that the units may be mated as best shown in Fig. iof the drawings, and these tile units may be attached to furring stripsll, IT or any other suitable part of a wall or ceiling as by mailing thebase pieces a, a oi the units thereto, as best indicated in Fig. 4 ofthe drawings. There results an acoustical tile assembly as shown inFigs. 3 and 4 of the drawings, which, in addition to functioning; asabove described, presents a very attractive and highly ornamental wallor. ceiling appearance.

The tile unit T in bein cut or excised from a slab or board of fibrousmaterial so as to produce the highly absorbent exposed faces 3, 3', maybe cut out substantially without waste from the slabs or boards (fromeither one board or I from a number of boards) Une way of doing this(ill is depicted in Figs. 5 and 6 of the drawings. A slab or board ofthe fibrous material generally designated as i8 is saw cut along "theclosed lines ll, 2i), 21 and 22 and at an inclination as shown in Fig. 6or the drawings, to produce the pieces a, b, c, d and c, as clearlyshown in these figures.

These excised pieces a to c are then rearranged inversely with respectto their original positions as shown in the exploded view of Fig. 7, andthe contiguous or contacting faces thereof are then joined together bysuitable cementing material to produce the pyramided assembly shown inFig. 2 of the drawings. In this way, the tile unit of Fig. 2 may beproduced, accomplishing all of the results of the latter, and may bemade from a single slab or board of the porous material substantiallywithout any waste.

These tile units may be also constructed to carry out certain featuresof my invention as described in my aforesaid copending applicationSerial No. 402,793, flied July 17, 1941, so as to predetermine thevibration frequency of the diaphragm part of the tile unit. This isshown in the modification of the structure illustrated in Figs. 8 and 9or the drawings. This structure, otherwise the same as that shown inFigs. 1 and 2 of the drawings and designated by similar refer- &

5 ence characters, exponented, however, with the numeral 2, has one ofits pieces or sections and preferably the section b slitted bodily as at23, 24, 25 and 26, leaving 29 and 30 (see Fig. 8). Because of these bodyslits, thev diaphragm portion of the unit now mainly consisting of thesections e'-, d, c and a part of b may vibrate more readily relative tothe remainder of the section b and the base a, the vibration being atthe bridge portions 21, 28, 29 and 30. This vibration particularly underthe impact of 'low frequency sound waves serves to dampen and absorb thesound waves as above described. The size of the tile unit, the length ofthe slits, the area or volume of the bridging portions, as well as theweight of the sound absorption material used, are all controllin factorsto predetermine the resonance frequency of the tile unit. By applyingthis improvement, the different. tiles of the invention may be made withone or more predetermined natural vibration frequencies; and the same ordifferent frequency tiles may be applied to a wall or ceiling, uniformlyor in appropriately staggered arrangement, to meet or solve the acousticproblem raised in any particular installation. I

A modification of the method and arrangement shown in Figs. 5 to 7 ofthe drawings is depicted in Figs. 10 and 11 of the drawings. In thismodification the sections or pieces a b d and e also cut or excised froma single slab or board of the sound absorbing material and producedsubstantially without any waste are so cut or excised that instead ofrearranging the pieces in inverse relation, these pieces may be movedout in telescopic relation to produce the finished assembly as depictedin-Fig. ll of the drawings. This is accomplished by making the saw-cutsis 20', M and 22'. relatively wide as indicated in Fig. 10 of thedrawings, wide enough to permit the parts to be moved into telescopiccondition shown in Fig. 11, the saw-cut being dimensioned, however, topermit the side faces of contiguous pieces to engage or meet and beunited to form an integral assembly, all as clearly depicted in Fig. 11of the drawings.

The tile unit may be made from a number of slabs or boards also withoutany substantial waste of material, and the tile pieces of differentboards may be assembled to produce a, tile unit such as shown, forexample, in Fig. 13 or Fig. 14 of the drawings. In Fig. 18, the tileunit is made up of the excised pieces a b 0*, d and e selected from a;number of different boards or slabs. In Fig. 14, the tile unit is madeup of the tile sections or pieces a b 0 d and a selected from two slabsor boards; thus, the sections or pieces a c and e may be cut from oneslab, while the sections 12 and d may be cut from .a second slab. Thetile units of Figs. 13 and 14 enable the obtaining of different areas ofexposed surfaces and also different areas of engagement between thepieces, both of which factors may be used as an additional control ofthe ultimate sound absorption characteristics (broken angular faces,extent of exposed surface and natural vibration frequency) of the tileunit.

The manner of making the tile unit of my present invention, thefunctioning thereof, and the many advantages to be obtained therebywill, in the main, be fully apparent from the above detailed descriptionthereof. By means of the tile of the present-invention, there isproduced an increase in the total area of absonbing ma terial which alsoincludes the exposing of'those bridging portions 21, 28,

6 portions most highly absorbent of the sound. Assuming that acommercial acoustic tile is made of /2" thick pulp or fibre board, is12" square, exposing 144 sq. in. to the sound waves, and has asound'absorption efliciency of the same tile-fabricatedin accord with myinvention would have, say, five steps to a pyramidal shape, would be 2%"thick and show an increased highly absorbing area of over 70 sq. in. Ifthis '70 sq. in. area'was not more absorbent than the surface of thematerial it would increase the efficiency of the tile about 15%-20%.This compares favorablywith the commercial perforated acoustic tilewhich is the material here mentioned with 464 perforations per sq. ft.,the holes being in diameter and deep, and has a sound absorption ofabout However, in comparison to the perforated fiat tile my tilepossesses additional sound absorbing efficiency due to the brokensurfaces and is many more times emcient inthe absorption of the lowfrequency sound waves due to the'diaphragm eifect. As actually measured,this low frequency absorption can be raised from a 20% efficiency of theflat effected by placing angularly shaped blocks at I tile at 256 cyclesto efficiency by the diahragm-impedance obtained. As each individualtile provided with this diaphragm effect will have a peak efiiciency inabsorbing certain low frequency sound waves, the spectrum of lowfrequency absorption can be broadened by using a series of tiles, say,four or more placed adjacent to one another, each so fabricated as torespond to a predetermined sound frequency.

While I have described my invention in some of its more preferred forms,it will be understood that many changes may be made in the structurethereof without departing from the spirit of the invention as defined inthe following claims. For example, the tiles may be made in other thanrectangular contours. The tile sections may considerably vary in number.The natural vibration frequency may be varie or predetermined by any ofthe means disclosed or by a suitable combinative selection of suchmeans; also, other means for determining the resonance frequency may beused; for example,

such resonance frequency may be predetermined by spacing some of thetile sections from the others by means of blocks positioned at the fourcomers. This separation may be preferably the four corners to separatethe base section of the tile from the superposed sections, such spacingblocks allowing the determining of the resonance frequency for eachtile. Many other modifications may be made. v

I claim:

1. An acoustic tile for walls and ceilings, said tile comprising aplurality of annular frames and a plaque all made of thick porouslight-weight sound-absorbing board laid face to face, said framesprogressively decreasing in size and being arranged in stepped relation,the largest frame forming the base of the tile and being attachable to awall or the like, and the plaque being smallest and vibratable andforming the apex of the tile, the exposed face of the tile therebypresenting an angularly broken and increased surface area for highfrequency sound absorption, and the central body of the tile beingvibratable for low frequency sound absorption.

2. An acoustic tile for walls and ceilings, said tile comprising aplurality of annular frames and a plaque all made of thick porouslight-weight 7 sound-absorbing board laid face to face, said framesprogressively decreasing in size and being arranged in stepped relation,the largest frame forming the base of the tile and being attachable to awall or the like, the plaque forming the apex of the tile, and therebeing at least one frame intermediate the base and the plaque, theexposed face of the tile thereby presenting an anguiarly broken andincreased surface area for sound absorption of the higher frequencies,and the base supported pieces being vibratable for sound absorption ofthe lower frequencies.

3. An acoustic tile according to claim 2, in which one of the basesupported pieces is bodily slitted except for bridging regions topredetermine the vibration frequency of the diaphragm part of the tile.

4. An acoustic tile according to claim 1 in which the overlappingportions of the sections are cemented to form the built-up tile.

5. An acoustic tile according to claim 2 in which the sections arecemented at overlapping contiguous faces to form a pyramided tile unit.

6. An acoustic tile for walls and ceilings, said tile comprising aplurality of annular frames and a plaque all made of thick porouslight-weight sound-absorbing board laid face to face, said board beingmore porous interiorly than at its face walls, said frames progressivelydecreasing in size and being arranged in stepped relation, the largestframe forming the attachable base of the tile, and the plaque beingsmallest and vibratile and forming the apex of the tile, said frames andplaque being cut, at their side edges to expose the more porous insidebody of the tile material, the exposed surface of the tile therebypresenting an angularly broken and increased area for high frequencysound absorption, and the central body of the tile being vibratile forlow frequency sound absorption.

\ largest frame forming the attachable base of the tile, the plaqueforming the apex of the tile, and there being at least one frameintermediate the base and the apex, the said pieces being cut at theirside edges to expose the more porous inside body of the tile material,and the base supported pieces being vibratile for sound absorption ofthe lower frequencies.

8. An acoustic tile for walls and ceilings, said tile comprising aplurality of annular frames and a plaque all made of thick porouslight-weight sound-absorbing board laid face to face, said framesprogressively decreasing in size and being arranged in stepped relationto form a pyramidal unit, the outermost frame forming the attachablebase of the tile, the plaque forming the apex of the tile, there beingat least one other frame intermediate the base and the apex.

9. The acoustic tile of claim 8, in which one of the base supportedpieces is bodily slitted except' at bridging regions thereof.

10. An acoustic tile as defined in claim 6, in which the frames andtheplaque have their edges cut at an acute angle to one face, the smallface of one section having an outside dimension corresponding to theinside dimension of the large face of the next section, said framesbeing united. with the large face of each section overlapping andcemented to the small face of the next section.

ALBERT B. HURLEY.

